The advent of combinatorial chemistry has sparked renewed interest in the use of functionalized polymers in the synthesis of small, organic molecules (for recent reviews, see Blackburn et al. "Functionalized Resins and Linkers for Solid-Phase Synthesis of Small Molecules", Drugs of the Future 1997, 22(9), 1007-1025; and Shuttleworth et al., "Functionalized Polymers: Recent Developments and New Applications in Synthetic Organic Chemistry", Synthesis 1997, 1217-1239). Inexpensive, readily prepared functionalized resins suitable for organic synthesis applications are increasingly needed.
Some thiol-functionalized polystyrene resins are known in the art. Literature methods for preparing thiomethyl-functionalized polystyrene resins involve multiple steps and give resins with low active SH titers unless significant care is taken to remove oxygen from all solvents and equipment (see J. Cerny and Wichterle, J. Polymer Sci. 1958, 30, 501, J. M. J. Frechet et al., Polymer 1979, 20, 675, and S. Kobayashi et al., Tetrahedron Lett. 1996, 37, 2809). Commercially available thiol-functionalized resins are expensive, have low loading and generally need pretreatment before use to remove a thiol protecting group.
Thiol-functionalized resins have found use as a solid phase support for the synthesis of substituted heterocycles (see Gayo and Suto, Tetrahedron Lett. 1997, 38, 211-214) and as supported nucleophiles to aid the purification of solution phase reactions involving excess electrophiles (Hodges, 2nd Winter Conference on Medicinal and Bioorganic Chemistry, Steamboat Springs, Colo., Jan. 26-31, 1997).